When using the backlog module we stumbled upon an issue when trying to sort issues on the "unassigned" side where the search bar is located. We are not sure if this is wanted or not, however it is essential for our company and customers to sort in this the backlog column. There is a error message appearing (see attached image). If this is intended behaviour, this ticket can be closed.

Logs:

Started PUT "/agile/board" for 10.47.1.85 at 2020-04-28 15:01:10 +0200
Processing by AgileBoardsController#update as */*
  Parameters: {"positions"=>{"1"=>{"position"=>"0"}, "2"=>{"position"=>"3"}, "3"=>{"position"=>"1"}, "4"=>{"position"=>"5"}, "5"=>{"position"=>"2"}, "6"=>{"position"=>"4"}, "7"=>{"position"=>"6"}, "8"=>{"position"=>"7"}, "9"=>{"position"=>"8"}, "10"=>{"position"=>"16"}, "11"=>{"position"=>"13"}, "12"=>{"position"=>"15"}, "13"=>{"position"=>"19"}, "15"=>{"position"=>"18"}, "17"=>{"position"=>"14"}, "18"=>{"position"=>"17"}, "20"=>{"position"=>"9"}, "25"=>{"position"=>"10"}, "26"=>{"position"=>"11"}, "27"=>{"position"=>"12"}}, "id"=>"2"}
  Token Update All (4.9ms)  UPDATE "tokens" SET "updated_on" = '2020-04-28 15:01:10.830941' WHERE "tokens"."user_id" = $1 AND "tokens"."value" = $2 AND "tokens"."action" = $3  [["user_id", 1], ["value", "4d8946d283df67647506946534e9d92818e7d2fc"], ["action", "session"]]
   (0.6ms)  SELECT MAX("settings"."updated_on") FROM "settings" 
  User Load (0.5ms)  SELECT  "users".* FROM "users" WHERE "users"."type" IN ('User', 'AnonymousUser') AND "users"."status" = $1 AND "users"."id" = $2 LIMIT $3  [["status", 1], ["id", 1], ["LIMIT", 1]]
  Current user: admin (id=1)
  Issue Load (0.4ms)  SELECT  "issues".* FROM "issues" WHERE "issues"."id" = $1 LIMIT $2  [["id", 2], ["LIMIT", 1]]
  Project Load (0.2ms)  SELECT  "projects".* FROM "projects" WHERE "projects"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
   (0.3ms)  SELECT "enabled_modules"."name" FROM "enabled_modules" WHERE "enabled_modules"."project_id" = $1  [["project_id", 1]]
  IssueStatus Load (0.4ms)  SELECT  "issue_statuses".* FROM "issue_statuses" WHERE "issue_statuses"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Tracker Load (0.5ms)  SELECT  "trackers".* FROM "trackers" WHERE "trackers"."id" = $1 LIMIT $2  [["id", 2], ["LIMIT", 1]]
  IssueCustomField Load (0.5ms)  SELECT "custom_fields".* FROM "custom_fields" WHERE "custom_fields"."type" IN ('IssueCustomField') AND (is_for_all = TRUE OR id IN (SELECT DISTINCT cfp.custom_field_id FROM custom_fields_projects cfp WHERE cfp.project_id = 1)) ORDER BY "custom_fields"."position" ASC
  IssueCustomField Load (0.5ms)  SELECT "custom_fields".* FROM "custom_fields" INNER JOIN "custom_fields_trackers" ON "custom_fields"."id" = "custom_fields_trackers"."custom_field_id" WHERE "custom_fields"."type" IN ('IssueCustomField') AND "custom_fields_trackers"."tracker_id" = $1  [["tracker_id", 2]]
  UserPreference Load (0.3ms)  SELECT  "user_preferences".* FROM "user_preferences" WHERE "user_preferences"."user_id" = $1 LIMIT $2  [["user_id", 1], ["LIMIT", 1]]
Completed 422 Unprocessable Entity in 46ms (Views: 0.1ms | ActiveRecord: 17.4ms)

System info of our test redmine instance:

Environment:
  Redmine version                4.1.1.stable
  Ruby version                   2.5.7-p206 (2019-10-01) [x86_64-linux]
  Rails version                  5.2.4.2
  Environment                    development
  Database adapter               PostgreSQL
  Mailer queue                   ActiveJob::QueueAdapters::AsyncAdapter
  Mailer delivery                smtp
SCM:
  Git                            2.17.1
  Filesystem                     
Redmine plugins:
  redmine_agile                  1.5.3

We are using the PRO-Version of the plugin.

As a rails developer I took a quick look at the source and found out modifying some javascript code quickly fixes the issue. I'm not sure if attaching a patch file here is allowed. If wanted I could provide one though.